Shoe stiffener blanks comprising polyvinyl chloride, an impact modifier and a layer of heat activatable adhesive

ABSTRACT

A thermoplastic shoe stiffener and stiffener blank comprising a nonfabric-containing sheet of thermoplastic polyvinyl chloride having a molding temperature of between 140* F. and 350* F. and containing an impact modifier, preferably linear polyethylene or linear-chlorinated polyethylene, in an amount between 3 and 18 percent by weight of the resin and a heat stabilizer in an amount equal to at least 1 percent by weight of the resin. The polyvinyl chloride contains a lubricant and may contain a plasticizer and filler. The stiffener is hard and tough and highly crush resistant but not brittle. It has excellent molding properties at the aforesaid temperatures, is water and mold proof, has a high flexure and tensile strength, an excellent memory for its molded shape upon deformation and an excellent recovery of its crush resistance after being crushed and then returned to its original shape. Unlike resin-impregnated fabrics, strength is not affected by the direction in which it is cut and it is equally stretchable in all directions. It is coated on one side with a layer of heat activatable adhesive and on the other side with a layer of flock or a layer of heat activatable adhesive.

United. States Patent Aaron Weinstein Marblehead;

Frank Scourtas, Newbury, both of Mass. [21] Appl. No. 732,833

[22] Filed May 29, 1968 [72] Inventors [45] Patented Dec. 21, 1971 [73]Assignee Pacesetter Products Inc.

Salem, Mass.

[52] US. Cl 161/64,

36/68, 36/77 M,1l7/16,l17/138.8UA,161/41, 161/167, 161/254, 161/256,260/31.8 M,

260/3l.8 DR

[51] Int. Cl ..D03d 27/00, B32b 27/08, B32b 27/30 [50] Field ofSearch161/151,

247, 250, 251, 253, 256, 82, 85, 84, 64; 36/68, 77, 77 M; 117/16, 138.8UA

[561 References Cited UNITED STATES PATENTS 2,611,195 9/1952 Brophy36/77 X 2,618,796 11/1952 Brophy 36/68 X Primary Examiner-John T.Goolkasian Assistant ExaminerC. B. Cosby Altorneys- Bronstein and DonaldBrown ABSTRACT: A thermoplastic shoe stiffener and stiffener blankcomprising a nonfabric-containing sheet of thermoplastic polyvinylchloride having a molding temperature of between 140 F. and 350 F. andcontaining an impact modifier, preferably linear polyethylene orlinear-chlorinated polyethylene, in an amount between 3 and 18 percentby weight of the resin and a heat stabilizer in an amount equal to atleast 1 percent by weight of the resin. The polyvinyl chloride containsa lubricant and may contain a plasticizer and filler. The stiffener ishard and tough and highly crush resistant but not brittle. It hasexcellent molding properties at the aforesaid temperatures, is water andmold proof, has a high flexure and tensile strength, an excellent memoryfor its molded shape upon deformation and an excellent recovery of itscrush resistance after being crushed and then returned to its originalshape. Unlike resin-impregnated fabrics, strength is SHOE STIFFENERBLANKS COMPRISING POLYVINYL CHLORIDE, AN IMPACT MODIFIER AND A LAYER OFHEAT ACTIVATABLE ADHESIVE BRIEF SUMMARY OF THE INVENTION The presentinvention relates to thermoplastic shoe stiffeners and shoe stiffenerblanks, the term shoe stiffener" including shoe counters, shoe toe boxesand shoe liners for maintaining the general shape of an upper made oflightweight materials. Particularly, the invention relates to suchthermoplastic stiffener blanks which are heated to a flaccid conditionand molded to the desired shoe shape during thermal forming of the upperand while assembled with that part of the shoe upper to which they areintended to impart stiffness. Accordingly, the stiffener and upper aremolded to the desired shape together in the same operation. Thestiffener and upper are maintained in their desired molded shape untilthe stiffener cools to its normal stiff state in which it retains itsmolded shape.

For many years, stiffeners, such as heel counters and toe boxes weremade of fiberboard, in some cases polyethylene, and were preformed.During lasting, the preformed stiffeners were assembled with and securedto the upper. In order to overcome certain disadvantages inherent withthese preformed stiffeners, in more recent years, flat or slightlycurved thermoplastic stiffener blanks have beenheated to a moldablestate and formed (molded) to the desired shape during the lastingoperation and while assembled with the shoe upper, as aforesaid.

In some cases, the thermoplastic stiffener blank is covered on one sidewith a layer of flock and on the other side with a layer of heatactivatable adhesive and the blank is stitched to the shoe upper withthe flocked side facing inwardly and with the adhesive covered sidelying against the upper or upper liner. The adhesive is activated at thethermal-forming temperature and the activated adhesive is pressedagainst the shoe upper during forming to bond the stiffener to theupper.

In other cases, the blank is covered on both sides with a heatactivatable adhesive and during the lasting operation it is inserted ina pocket in the upper, the inner wall of which comprises a liner. Theadhesive is activated at the thermal-forming temperature and theactivated adhesive is pressed against the walls of the pocket duringforming to bond the stiffener to the walls of the pocket.

lt is essential that the thermoplastic stiffener blank be easily andhighly moldable to the complex shapes required at the relatively lowtemperatures (l40-350 F.) used in conventional shoe forming operations(these temperatures must be low so as not to harm the shoe materials).lt must also be strong, hard and stiff at normal temperatures to whichthe shoe may be expected to be subjected without being brittle. It mustbe highly resilient and resistant to crushing and have a good memory forreturning to its molded shape when deformed. It must exhibit goodrecovery of crush resistance after it has been crushed and returned toits original molded shape. It must have a high-flexure strength, ahigh-tear resistance and a high-tensile strength. Furthermore, it mustbe capable of being stitched to the upper without pulling away from thestitches in those cases where r is assembled with the upper bystitching.

Commercial thermoplastic stiffener blanks have heretofore been made of afabric, such as flannel, impregnated or saturated with a thermoplasticresin, such as polyvinyl acetate, polyvinyl chloride, polyethylene, etc.Laminates of one or more plies of fabric and thermoplastic resin havebeen proposed. See U.S. Pat. Nos. 2,619,441; 2,684,540; 3,170,252;3,174,236; 3,234,668 and 3,257,743.

Fabric has been and is still considered necessary in conventionalthermoplastic stiffener blanks in order to reinforce and support theresin. The reasons for this are as follows: Heretofore, resins whichhave been proposed and which have possessed the required properties oftoughness, low brittleness, high-crush resistance and ductility and highmoldability at the relatively low temperatures used in conventional shoeforming operations, have not been strong enough (they are too soft andtear too easily) or cohesive enough without a fabric reinforcement andsupport to hold them together and give them body. For example, whenthese resins are used without a fabric, the counter tends to pull awayfrom the stitching securing it to the upper and the stitching tends tobreak the counter. However, the included fabric has the followingdisadvantages: (1) it decreases the moldability of the hot blanks; (2)it absorbs moisture, e.g., perspiration during use, resulting insoftening and deterioration of the stiffener and the possibledevelopment of mold and odor-producing bacteria; (3) the stiffenerstrength varies depending on the direction in which it is cut and,accordingly, if it is cut in the wrong direction, its strength isdecreased; (4) the counter is not equally stretchable in all directionswhich may result in breakage during molding; (5) the fabric may causethe edges of the cut counter blanks and counters to fray; (6) the crushresistance (strength) of the counter and its memory for returning to itsmolded shape when deformed are limited probably because the interfacesbetween the fabric and resin constitute weak places which are apt tocrack and because the fabric itself has a poor memory and a poor crushresistance. Furthermore, impregnation of the fabric with the resin andlamination are expensive.

A nonfabric-containing thermoplastic polystyrene heel counter has beensuggested in U.S. Pat. No. 3,144,670 filed Jan. 5, 1961. The fabric canbe omitted from this counter because polystyrene sheets can becompounded to have sufficient stiffness and hardness to hold up withouta fabric while still having molding properties which permit them to beused under conventional thermal-forming conditions. However, when socompounded, they are too brittle. For example, they are too brittle tobe satisfactorily stitched to the upper. Furthermore, this brittlenessgives them low-crush resistance and poor flexure strength. In short,although polystyrene sheets can be compounded to have those desirableproperties which do not require a fabric foundation they have otherproperties which prevent them from making a satisfactory shoe stiffener.Accordingly, they have not met with commercial success as shoestifieners and thennoplastic resin-impregnated fabrics are still themost widely used thermoplastic shoe stiffeners in spite of theiraforesaid disadvantages.

The present invention provides an improved thermoplastic shoe stiffenerhaving important advantages over conventional thermoplasticresin-impregnated fabric stiffeners. Because it does not employ a fabricfoundation it is uniformly stretchable in all directions, it can be cutin any direction and still have the same strength, it is water andmoisture proof, it is highly bacteria and mold resistant, it does notfray at the edges and it has better molding properties. On the otherhand, it is not brittle. It is more crush and impact resistant, has agreater recovery of crush resistance after being crushed and returned toits original shape, has a greater memory for returning to its originalshape when deformed, is tougher and stronger, has a greater resistanceto permanent deformation and has greater wearability, hardness andstiffness and a higher tear, flexure and tensile strength thanconventional thennoplastic counters employing fabrics. Accordingly, thestiffener blank of the invention can be securely stitched to the upperwithout breaking and without danger of pulling away from the upper.Furthermore, the stiffener blank of the invention can be made thinnerthan conventional resin-impregnated fabrics, which is highly desirablefor certain uses.

The shoe stiffener of the present invention comprises anonfabric-containing thermoplastic sheet consisting essentially of (l) athermoplastic polyvinyl chloride resin of low to medium molecular weightand moldable at a temperature of between about F. and 350 F., (2) animpact modifier for said resin and compatible with said resin andpresent in an amount equal to between about 3 and 18 percent, preferablybetween about 4 and 15 percent and more preferably between about 5 and10 percent, by weight of the resin, and (3) a heat-stabilizing compoundfor said resin present in an amount equal to at least 1 percent,preferably between about i and 7 percent and more preferably between iand percent, by weight of the resin.

When it is stated in the specification and claims hereof that the resinsheet does not contain a fabric, e.g., nonfabric-containingthermoplastic sheet, it is meant that it does not contain a fabricembedded therein to form a skeleton for the resin as in the case ofresin-impregnated fabrics. However, this terminology does not excludelaminating the polyvinyl chloride resin sheet with a fabric, (e.g., by alayer of adhesive or cement) which is not wholly embedded therein.

Preferably, one side of the sheet has a layer of dry heat activatableadhesive adhered thereto, and the other side has adhered thereto eithera layer of flock or a layer of dry heat activatable adhesive.

The unique properties of the aforesaid thermoplastic polyvinyl chlorideresin sheet make it possible to omit a fabric ply foundation and itsaforesaid disadvantages without loss of cohesiveness and strength. Thus,the resin sheet is hard and strong enough so that a reinforcing fabricis not required and yet it is not brittle but rather is quite resilientand crush resistant with an excellent memory and an excellent recoveryof t such memory after crushing.

These polyvinyl chloride sheets are ductile, relatively inexpensive andhave a low volatility.

Homopolymers of vinyl chloride are preferred but copolymers of vinylchloride and minor amounts, preferably between 3 and 5 percent but ashigh as [O or in some cases 15 percent by weight of the total resin, ofother unsaturated monomers, such as vinyl acetate, methyl methacrylate,maleic anhydride, etc. can be used, according to conventional practicein the manufacture of polyvinyl chloride copolymers. The term polyvinylchloride" is used herein to include both these homopolymers and thesecopolymers.

A preferred range of molecular weights of the polyvinyl chloride arethose giving a relative viscosity ASTM D 1,755-60-2 and 5, preferablybetween about 2 and 4. These are typically low to medium molecularweight vinyl chloride polymers. When the sheet is extruded a highermolecular weight can be used as compared to when it is calendered.

Preferred impact modifiers are linear polyethylene and linearchlorinated polyethylene. However, acrylic, e.g., polymethylmethacrylate (homopolymers of methacrylate are sold under the tradenameACRYLOID by Rohm and Haas Company), ABS(acrylonitrile-butadiene-styrene), acrylonitrile-butadiene, andstyrene-butadiene polymers may also be used.

Preferably the sheet is either calendered or extruded, although it maybe cast, and contains a conventional lubricant, such as stearic acid,zinc, calcium or other metal stearates, paraffin wax, mineral oil,silicones, etc. present in an amount equal to between about 0.1 and 4percent, preferably between about 0.1 and 1 to 2 percent and morepreferably between about 0.5 and 1 percent, by weight of the resin.Where the sheet is extruded a wax (0.1-4 percent by weight of theresin), is preferred but when it is calendered, stearic acid or zinc,calcium or other metal stearates (O.25l%percent by weight of the resin)is preferred.

The sheet may also contain a plasticizer, preferably dioctyl phthalate,for the polyvinyl chloride in an amount equal to between about and 20percent, preferably -20 percent, by weight of the resin and a filler,preferably calcium carbonate, in an amount equal to between about 5 and30 percent, preferably between about 10 and 25 percent and morepreferably between about 10 and percent, by weight of the resin. Aplasticizer and filler are preferred when the sheet is calendered butnot when it is extruded.

Certain heat stabilizers, such as epoxidized compounds, e.g., oils suchas soy bean oil, also function as plasticizers. Accordingly, where suchheat stabilizers are used, the amount of plasticizer can be reduced bythe amount of such heat stabilizer.

Where a plasticizer is used, it is preferable to use a filler to offsetthe softness introduced by the plasticizer. The filler does this byadding to the stiffness. The correct amount of filler and plasticizerare therefor interrelated. For example, if more plasticizer is used,more filler is required to compensate for the loss in stiffness causedby the increased amount of plasticizer. If too much filler is used, thesheet may be rendered too brittle, and if too little is used compared tothe amount of plasticizer, the sheet may be too soft. However, theplasticizer and filler can both be omitted. The polyvinyl chloridesheets with plasticizer are generally not as rigid as those withoutplasticizer, i.e., the plasticizer makes the sheet softer. The rigiditydepends on the amount of plasticizer used. The counters of the inventionmay be quite rigid or semirigid.

The addition of plasticizer also lowers the softening point of the resinsheet to thereby lower the molding temperature.

Illustrative of the conventional plasticizers which can be used are theadipates, such as dioctyl adipate, the sebacates and the azelates,epoxidized oils, the phthalates such as diphenyl phthalate, diisooctylphthalate, diisodecyl phthalate and butyloctyl phthalate, thephosphates, such as tri( paratertiary butylphenyl) phosphate, long chainfatty acid esters, chlorinated diphenyls, camphor, pyronones, benzoylacetone, the sulfonamides, such as ethyl o-toluene sulfonamide, etc.However, diisooctyl phthalate is by far preferred.

Illustrative of the fillers, which can be used, are the clays andsilicas. However, calcium carbonate is by far preferred.

lllustrative of the conventional heat stabilizers which can be used areoxirane compounds such as epoxidized soy bean oil (these have aplasticizing effect as well as a stabilizing effect), cadmium and bariumfatty acid salts, i.e., the cadmium and barium soaps (e.g., stearate,octoate and oleate), cadmium and barium naphthenates, tin fatty acidsalts (tin stearate, tin oleate, tin octoate, etc.), alkyl tin soapssuch as dibutyl tin dilaurate, tin naphthenates, alkyl tin mercaptides,phosphite esters, polyphosphites, basis lead salts, calcium carbonate,cal cium and barium soaps (e.g., stearate, octoate and oleate), calciumand barium naphthenates, etc.

When a plasticizer and filler are used and the sheet is calendered,epoxidized soy bean oil (between 2 and 7 percent by weight of the resin)is preferred as part of the plasticizer and as the heat stabilizer andwhen they are not used and the sheet is extruded, a tin soap stabilizer(between 1 and 5 percent, preferably i k-2 percent, by weight of theresin) is preferred.

in addition, a pigment or pigments, may be added to the sheet forcoloring.

It is pointed out that the plasticizer, the impact modifier, the vinylacetate or other minor component of the vinyl chloride copolymer when ithas such a component and the stabilizer in some instances, e.g.,epoxidized oils, all tend to increase the softness (decrease thestiffness and hardness) of the resin. Accordingly, if no plasticizer isused and the polyvinyl chloride is a homopolymer, greater amounts ofimpact modifier may be used. On the other hand, when a plasticizer or avinyl acetate component is used, the amount of impact modifier may beless. When a plasticizer is used, the amount thereof, when added to theamount of impact modifier, and vinyl acetate component of the polyvinylchloride resin, should not be so great as to soften the resin too much.However, it should be remembered that because the filler tends to offsetthe softness caused by the plasticizer, it permits the use of a greateramount than would otherwise be practical. in order to achieve adequatestiffness, the total amount of impact modifier, plasticizer (includingthose stabilizers such as epoxidized oils which function asplasticizers) and vinyl acetate or other minor copolymeric component ofthe polyvinyl chloride which tends to have a softening effect, shouldpreferably not be more than 40 to 42 percent, more preferably not morethan 32 to 35 percent, of the total weight of the vinyl chloride in theresin (exclusive of the vinyl acetate or other copolymeric minorcomponent, if any). Still more preferably, it should not be more than 25to 30 percent by weight of the vinyl chloride in the resin.

The polyvinyl chloride sheet without the flock and heat activatablecoatings has a Tinius Olsen ASTM D 747-6l-T Stiffness test result of atleast 0.4 or 0.45 (40 or 45 scale reading at 60 deflection) andpreferably at least 50. A Tinius Olsen stiffness of between 50 and 100is preferred. A Tinius Olsen stiffness of between 0.63 and 0.73 (63-73scale reading) for a 28 gauge (28 mil) sheet thickness is an adequatestiffness.

The hardness of the sheet is at least 45 or 50 and preferably at least55 measured by the Shore D Durometer SATM D1706 test. A sheet having aShore D test value of between 60 and 65 has proven satisfactory.

The brittleness should not be less than about 3 lbs., preferably notless than 4 or 5 lbs., measured by the Falling Dart Impact test.Preferably, it should be between 8 and 10 lbs. or more according to thistest. The impact resistance of the sheet is not measurable accurately bythe standard Izod test. The Falling Dart Impact test consists ofclamping a sheet of standard thickness and at a standard temperature anddropping on it, from a standard height of 26 inches, a dart weighing l%pounds and having a hemisphere head of A-inch diameter at a standardtemperature with weights attached to the dart. The weights are increaseduntil the sheet breaks. The polyvinyl chloride sheet falls within arelatively high-speed class according to the ASTM D882 tensile breakingload test, e.g., 20 inches/minute. A sheet having an ASTM D882 tensilebreaking load of between 150 and 175 No. with an elongation of 80-100percent at a speed of 20 inches per minute has proven quitesatisfactory.

The flexural strength of the polyvinyl chloride sheet after coating withflock and heat sensitive adhesive is relatively high compared toconventional thermoplastic stiffeners, e.g., it has a flex strengthaccording to the ASTM D1052 Ross Flex Test (complete failure with a flexcycle of 180 bend) of between 300 and 700, depending on thickness.

The dry thermoplastic heat activatable adhesive applied to one or bothfaces of the polyvinyl chloride sheet may be of conventional type whichis compatible with polyvinyl chloride, Illustrative of such adhesive arethose based on ethyl cellulose, styrenebutadiene-rubber, rubber,polyvinyl chloride resins and copolymers, butyl rubber (GR-l0), GR-Nbutadiene-acrylonitrile rubber, vinyl acetate, ethylene vinyl acetatecopolymers, polyurethanes, polyesters, polyamides, etc. Mixtures ofthese materials with waxy components such as paraffin wax and the higherfatty acids and their salts, e.g., stearic acid, oleic acid and theirmetal salts, waxy alkyd resins, etc. and/or with modifiers such aspolystyrene latices and resins, ethylene-vinyl acetate copolymers,polyterpenes, other resins such as a-or B-pinene, gum rosin and gumrosin esters. The adhesive is applied as a hot melt or as an organicsolution or an aqueous latex emulsion and the carrier is removed byheating so that the adhesive is adhered to the polyvinyl chloride as adry coating.

Where a layer of flock fibers is applied to one side of the polyvinylchloride sheet it is bonded to the sheet by means of any conventionalthermoplastic adhesive compatible with the polyvinyl chloride sheet.Such adhesive may be of the same type as that applied to the adhesiveside of the sheet or it may be comprised of acrylic (acrylic esters suchas polymethylmethacrylate) latices, polyacrylonitrile latices, etc. Awater based synthetic latex containing a surfactant, such aspolyethylene oxide ester of sorbitan or mannitan, is preferred. Also,like compounds in solvent, e.g., toluene, may be used. The adhesive isapplied to the polyvinyl chloride sheet as a layer in the form of asolution or emulsion. The flock is applied to the wet adhesive layerfollowed by evaporation of the carrier and curing of the adhesive by theapplication of heat.

The finished coated stiffener blanks of the invention when used forcounters and toe boxes may vary in thickness between 4 and 50 mils (forcounters between 18 and 50 mils and for box toes between 4 and 30 mils).The base polyvinyl chloride sheet of such blanks may vary in thicknessbetween 4 and 40 mils. The thickness of the flock layer (flock andadhesive bonding it to the polyvinyl chloride sheet) may vary between5-20 mils and the thickness of the heat activatable adhesive may varybetween l] 0 mils.

Not only are the stiffener blanks of the invention useful for counterand toe box stiffeners but they may also be used as a liner to form ashape-retaining skeleton for uppers made of very thin material. When soused, they are in the form of a thin, more flexible sheet, the totalthickness of which may be between 3 and 20 mils. They can be used inthis way with dry heat activatable adhesive on one side and flock on theother or with heat activatable adhesive on both sides. Because of thelight weight of these shoe materials, something is needed to hold theupper to the form of the shoe.

DETAILED DESCRIPTION Example 1 In this example, the polyvinyl chloridesheet consisted of an extruded sheet 20-22 mils in thickness and havingthe following composition:

One-hundred parts homopolymer of a medium molecular weight unplasticizedpolyvinyl chloride (relative viscosity ASTM D 1755-60-T value of 3.5)

Seven parts linear polyethylene (impact modifier) 1V2 parts of tin soap(stearate) (heat stabilizer) Three-fourths part paraffin wax lubricantThis resin sheet had an average Tinius Olsen ASTM D 747-61-60 across thelines of orientation of the sheet and 65 parallel to the lines oforientation, a Shore D Durometer ASTM D 1706 Hardness of 63, and anaverage ASTM D882 tensile breaking load of 161 lbs. (7,800 p.s.i.) at 20inches per minute with a elongation of -100 percent.

To one side of this sheet was applied a GR-S butadienestyrene solutionin methyl ethyl ketone solvent followed by evaporation of the solvent toform a layer (about 2-mils thick) of dry heat activatable adhesive uponcooling.

To the other side of the sheet there was applied a layer of abutadiene-styrene latex to which was applied a layer of flockingmaterial. The flock fibers adhered to the wet butadiene-styrene layer.The latex was then dried and cured by heating. This flock layer wasabout 12 mils thick.

The resulting sheet had a Tinius Olsen ASTM D 747-6 l-T test value of 65across the lines of orientation of the sheet and 68 parallel to thelines of orientation, a Shore D Durometer ASTM D 1,706 hardness of 57,an average ASTM D882 tensile-breaking load of l67 lbs. (5,000 p.s.i.) at20 inches per minute with an elongation of 80-100 percent and an ASTM D1052 Ross Flex value of 400.

The resulting sheet was cut into counter blanks, each of which wasstitched in conventional manner to back part of a shoe upper with theflocked surface facing inwardly and the adhesive surface facing theupper. These uppers were preheated in a 350 F. oven with a dwell periodsufficient to render the polyvinyl chloride sheet moldable and toactivate the layer of heat activatable adhesive adjacent the upper.Thereafter the back parts of the uppers were formed in conventionalmanner on a conventional thermal back part forming machine, involvingthe steps of pulling the upper over the last to mold the back part ofthe upper to the last and wiping in the lower margin under the insole.The heated thermoplastic counter blanks molded well to the shape of thelast and at the same time the heat activated adhesive layer bonded themolded counter blanks firmly to the uppers. The lower margins of the hotcounter blanks were wiped in with the lower margins of the uppers.Within a minute after the wiping in step the molded counters cooled tohardness. In each case, the resulting counter was tougher and more crushresistant, and had a greater flexure strength, tear resistance andmemory upon deformation than counters made in the same way fromconventional resin-impregnated fabric counter blanks. Furthermore,recovery of its resistance to crushing and of its memory after it wascrushed and then returned to its original shape was much better. Thus,it resisted flexing more and upon flexing it returned to its originalposition much more readily than the resin impregnated fabric counters.Further more, it could be flexed many more times than the resinimpregnated fabrics before its back" was broken, i.e, before it nolonger exhibited the property of returning to its original shape.Furthermore, even after its back was broken, it did not go nearly aslimp as the resin-impregnated fabric counters It maintained its standupstrength and stiffness much better than the resin-impregnated fabrics.Furthermore, in spite of the fact that it did not contain fabric, itstitched better than the resin impregnated fabric counters. It did notpull away from the stitching.

EXAMPLE 2 Example 2 was the same as example I, except that the polyvinylchloride sheet was calendered and had the following composition:

One-hundred parts of low to medium molecular weight polyvinyl chloridehomopolymer having a molecular weight relatively viscosity ASTM D1755-60-T test value of 3.

Seventeen parts diisooctyl phthalate (plasticizer) Fifteen parts calciumcarbonate (filler) Three parts epoxidized soy bean oil (heat stabilizer)k-part calcium stearate (lubricant) Between 4 and 5 parts ofacrylonitrile-butadiene-styrene copolymer (impact modifier) This sheethad a Falling Dart lmpact Test value of between 8 and 9 lbs., aTinius-Olsen ASTM D747-6l-T test value of 82 across the lines oforientation and 92 parallel to the lines of orientation and a thicknessof 28 mils. It had an ASTM D1706 Shore D value of 65 and an average ASTMD882 tensilebreaking load of 160 pounds (5,670 psi.) at a speed ofinches per minute with an elongation of 80l 00 percent.

A heat activatable layer was applied to one side of this sheet and alayer of flock was applied to the other side in the same manner asexample 1 except that the heat activatable layer was applied as anaqueous butadiene-styrene latex followed by drying.

The resulting sheet had an ASTM D7476l-T Tinius Olsen value of 90 acrossthe lines of orientation and 98 parallel to the lines of orientation, anASTM D1706 Shore D hardness of 63, an ASTM D882 tensile-breaking load of168 pounds (4,400 p.s.i.) at a speed of 20 inches per minute with anelongation of 80l00 percent and an ASTM D1052 Ross Flex value of 700.

The heel counters formed from blanks of this composite sheet in the samemanner as example 1 (except that a preheat temperature of 250 F. wasused because the resin had a lower softening point) compared favorablywith those of example 1. The counter of example 2 took about 1% minutesto cool to stiffness after the wiping-in step.

Although in the aforesaid examples, the counter was molded on the last,it may be molded, while assembled with the upper, on a hot or cold formfollowed by lasting.

We claim:

1. A shoe stiffener blank comprising a thermoplastic sheet which is freefrom any fabric or fibrous sheet foundation embedded therein, which issoft and moldable at elevated temperatures but hard and stiff at normaltemperatures and which consists essentially of a thermoplastic polyvinylchloride resin moldable at a temperature of between 350 F. andcontaining an impact modifier for increasing the impact resistance ofsaid resin of and a heat-stabilizing compound for said resin present inan amount equal to at least 1 percent by weight of the resin, at leastone side of said sheet having a layer of dry heat activatable adhesiveadhered thereto, said impact modifier being selected from the groupconsisting of butadiene styrene copolymer, acrylonitrile-butadienecopolymer, linear polyethylene and acrylonitrile-butadiene-styrenecopolymer present in an amount equal to between about 3 and l8-percentby weight of the resin.

2. A shoe stiffener blank according to claim 1, the other side havingadhered thereto a layer ofa material selected from the group consistingof flock and dry heat sensitive adhesive.

3. A shoe stiffener blank according to claim 1, said resin containing alubricant present in an amount equal to between about 0.1 and 4 percentby weight of the resin.

4. A shoe stiffener blank according to claim 1, said resin alsocontaining a plasticizer for said polyvinyl chloride in an amount equalto between about 10 and 20 percent by weight of said resin.

5. A shoe stiffener blank according to claim 4, said resin containing anamount of filler between 5 and 30 percent by Weight of said resin, saidplasticizer being a dialkyl phthalate.

6. A shoe stiffener blank according to claim 5, said filler beingcalcium carbonate and said heat stabilizer being selected from the groupconsisting of an organic oxirane and cadmium, barium and tin fatty acidand naphthenate salts and being present in an amount equal to betweenabout 2 and 7 percent by weight of said resin, said polyvinyl chloridesheet being a calendered sheet.

7. A shoe stiffener blank according to claim 4, said resin containing alubricant selected from the group consisting of stearic acid, a metalstearate and a wax.

8. A blank according to claim 1, said sheet being an ex truded sheet.

9. A shoe stiffener blanl: according to claim 1, said polyvinyl chloridehaving a molecular weight giving a relatively viscosity ASTM D l75560Ttest value between about 2 and 5.

10. A shoe stiffener blank according to claim 9, said resin having amolecular weight giving a relative viscosity ASTM D 1755-60-2 and 4.

11. A shoe stiffener blank according to claim 2, said materi a1 beingflock adhered to said polyvinyl chloride sheet by an adhesive layer.

12. A shoe stiffener blank according to claim 1, said blank being a shoecounter blank.

13, A shoe stiffener blank according to claim 1, said blank being a shoetoe box blank.

14. .A shoe stiffener blank according to claim 1, said amount of impactmodifier being between about 4 percent and 10 percent by weight of theresin.

15. A shoe stiffener blank according to claim 1, said impact modifierbeing a butadiene polymer.

2. A shoe stiffener blank according to claim 1, the other side havingadhered thereto a layer of a material selected from the group consistingof flock and dry heat sensitive adhesive.
 3. A shoe stiffener blankaccording to claim 1, said resin containing a lubricant present in anamount equal to between about 0.1 and 4 percent by weight of the resin.4. A shoe stiffener blank according to claim 1, said resin alsocontaining a plasticizer for said polyvinyl chloride in an amount equalto between about 10 and 20 percent by weight of said resin.
 5. A shoestiffener blank according to claim 4, said resin containing an amount offiller between 5 and 30 percent by weight of said resin, saidplasticizer being a dialkyl phthalate.
 6. A shoe stiffener blankaccording to claim 5, said filler being calcium carbonate and said heatstabilizer being selected from the group consisting of an organicoxirane and cadmium, barium and tin fatty acid and naphthenate salts andbeing present in an amount equal to between about 2 and 7 percent byweight of said resin, said polyvinyl chloride sheet being a calenderedsheet.
 7. A shoe stiffener blank according to claim 4, said resincontaining a lubricant selected from the group consisting of stearicacid, a metal stearate and a wax.
 8. A blank according to claim 1, saidsheet being an extruded sheet.
 9. A shoe stiffener blank according toclaim 1, said polyvinyl chloride having a molecular weight giving arelatively viscosity ASTM D 1755-60-T test value between about 2 and 5.10. A shoe stiffener blank according to claim 9, said resin having amolecular weight giving a relative viscosity ASTM D 1755-60-T test valuebetween about 2 and
 4. 11. A shoe stiffener blank according to claim 2,said material being flock adhered to said polyvinyl chloride sheet by anadhesive layer.
 12. A shoe stiffener blank according to claim 1, saidblank being a shoe counter blank.
 13. A shoe stiffener blank accordingto claim 1, said blank being a shoe toe box blank.
 14. A shoe stiffenerblank according to claim 1, said amount of impact modifier being betweenabout 4 percent and 10 percent by weight of the resin.
 15. A shoestiffener blank according to claim 1, said impact modifier being abutadiene polymer.